Company Is Expected to Unveil New Metrics That Will Show Breadth of Its Audience

After a troubling start as a public company, Twitter Inc. plans to try out some new numbers on Wall Street.

When it reports second-quarter earnings on July 29, the San Francisco company is expected to unveil as many as four new metrics that it hopes will illustrate its reach beyond the 255 million users that log in at least once a month, according to people familiar with the matter. The aim: to show Twitter isn't just a diminutive...